πŸ’Ύ Archived View for gmi.noulin.net β€Ί man β€Ί man3 β€Ί sighold.3.gmi captured on 2024-08-31 at 14:17:52. Gemini links have been rewritten to link to archived content

View Raw

More Information

⬅️ Previous capture (2022-06-12)

-=-=-=-=-=-=-

SIGSET(3)                                                               Linux Programmer's Manual                                                              SIGSET(3)

NAME
       sigset, sighold, sigrelse, sigignore - System V signal API

SYNOPSIS
       #include <signal.h>

       typedef void (*sighandler_t)(int);

       sighandler_t sigset(int sig, sighandler_t disp);

       int sighold(int sig);
       int sigrelse(int sig);
       int sigignore(int sig);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       sigset(), sighold(), sigrelse(), sigignore():
           _XOPEN_SOURCE >= 500

DESCRIPTION
       These  functions  are provided in glibc as a compatibility interface for programs that make use of the historical System V signal API.  This API is obsolete: new
       applications should use the POSIX signal API (sigaction(2), sigprocmask(2), etc.)

       The sigset() function modifies the disposition of the signal sig.  The disp argument can be the address of a signal handler function, or  one  of  the  following
       constants:

       SIG_DFL
              Reset the disposition of sig to the default.

       SIG_IGN
              Ignore sig.

       SIG_HOLD
              Add sig to the process's signal mask, but leave the disposition of sig unchanged.

       If disp specifies the address of a signal handler, then sig is added to the process's signal mask during execution of the handler.

       If disp was specified as a value other than SIG_HOLD, then sig is removed from the process's signal mask.

       The dispositions for SIGKILL and SIGSTOP cannot be changed.

       The sighold() function adds sig to the calling process's signal mask.

       The sigrelse() function removes sig from the calling process's signal mask.

       The sigignore() function sets the disposition of sig to SIG_IGN.

RETURN VALUE
       On  success, sigset() returns SIG_HOLD if sig was blocked before the call, or the signal's previous disposition if it was not blocked before the call.  On error,
       sigset() returns -1, with errno set to indicate the error.  (But see BUGS below.)

       The sighold(), sigrelse(), and sigignore() functions return 0 on success; on error, these functions return -1 and set errno to indicate the error.

ERRORS
       For sigset() see the ERRORS under sigaction(2) and sigprocmask(2).

       For sighold() and sigrelse() see the ERRORS under sigprocmask(2).

       For sigignore(), see the errors under sigaction(2).

ATTRIBUTES
       For an explanation of the terms used in this section, see attributes(7).

       β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
       β”‚Interface                                                                                                                             β”‚ Attribute     β”‚ Value   β”‚
       β”œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€
       β”‚sigset(), sighold(), sigrelse(), sigignore()                                                                                          β”‚ Thread safety β”‚ MT-Safe β”‚
       β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜

CONFORMING TO
       SVr4, POSIX.1-2001, POSIX.1-2008.  These functions are obsolete: do not use them in new programs.  POSIX.1-2008 marks sighold(),  sigignore(),  sigpause(3),  si‐
       grelse(), and sigset() as obsolete, recommending the use of sigaction(2), sigprocmask(2), pthread_sigmask(3), and sigsuspend(2) instead.

NOTES
       These functions appeared in glibc version 2.1.

       The sighandler_t type is a GNU extension; it is used on this page only to make the sigset() prototype more easily readable.

       The sigset() function provides reliable signal handling semantics (as when calling sigaction(2) with sa_mask equal to 0).

       On  System  V,  the signal() function provides unreliable semantics (as when calling sigaction(2) with sa_mask equal to SA_RESETHAND | SA_NODEFER).  On BSD, sig‐
       nal() provides reliable semantics.  POSIX.1-2001 leaves these aspects of signal() unspecified.  See signal(2) for further details.

       In order to wait for a signal, BSD and System V both provided a function named sigpause(3), but this function has a different argument on the two  systems.   See
       sigpause(3) for details.

BUGS
       In versions of glibc before 2.2, sigset() did not unblock sig if disp was specified as a value other than SIG_HOLD.

       In  versions  of  glibc  before  2.5,  sigset()  does  not  correctly return the previous disposition of the signal in two cases.  First, if disp is specified as
       SIG_HOLD, then a successful sigset() always returns SIG_HOLD.  Instead, it should return the previous disposition of the signal (unless the signal  was  blocked,
       in  which case SIG_HOLD should be returned).  Second, if the signal is currently blocked, then the return value of a successful sigset() should be SIG_HOLD.  In‐
       stead, the previous disposition of the signal is returned.  These problems have been fixed since glibc 2.5.

SEE ALSO
       kill(2), pause(2), sigaction(2), signal(2), sigprocmask(2), raise(3), sigpause(3), sigvec(3), signal(7)

Linux                                                                          2021-03-22                                                                      SIGSET(3)